Monitoring device for vehicles, in particular, motor vehicles

ABSTRACT

A monitoring device for vehicles has a housing and at least one mirror glass arranged in the housing so as to have a front side facing an observer. The at least one mirror glass has a reflective layer being reflective in the visible spectral range of light. At least one camera is arranged behind the reflective layer in a viewing direction viewed from the front side. The monitoring device can be used for driver identification, monitoring the driver&#39;s condition, identifying passengers and passenger positions, controlling airbags, theft surveillance, and similar purposes.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a monitoring device for vehicles, inparticular, motor vehicles, comprising a mirror glass behind which atleast one camera is arranged.

[0003] 2. Description of the Related Art

[0004] Interior rearview mirrors of motor vehicles are known which areprovided with a sensor. In order for the sensor to fulfill its function,the mirror glass is provided with a cutout. However, cutouts in thereflective layer of mirror glass are generally not acceptable foresthetic reasons. Often, it is also desired that the sensor beinvisible. Moreover, there are also regulations in the automobileindustry which concern the geometric size of the mirror surface.

SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to configure themonitoring device of the aforementioned kind such that the camera is notvisible behind the mirror glass, but such that the mirror glass stillcan fulfill its function reliably.

[0006] In accordance with the present invention, this is achieved inthat the mirror glass comprises a reflective layer which is reflectivewithin the visible spectral range of light and behind which the camerais arranged.

[0007] In the monitoring device according to the invention, the camerais positioned behind the reflective layer which is designed to reflectpreferably up to 50% within the visible spectral range of light.Accordingly, the camera is not visible behind the mirror glass while themirror glass has the desired high reflection. When the mirror glass is,for example, used as an interior rearview mirror of a motor vehicle, thereflective layer has a reflective spectrum for reflecting light with theminimum percentage required pursuant to the regulations for automotivemirrors. Advantageously, the camera is a CCD (charge coupled device)camera or CMOS (complementary metal oxide semiconductor) camera. Themirror glass with the reflective layer is sufficiently transparentwithin the near infrared range that video images can be taken with sucha camera. In the case that the illumination is not sufficient, it ispossible to provide additional illumination by means of an auxiliarylighting unit, preferably in the form of LEDs (light-emitting diodes)which emit a wavelength for which the reflective layer is sufficientlytransparent and for which the camera has a satisfactory sensitivity. Inthe case of bad lighting situations within the visible range, therequired area can be additionally illuminated, undetected by the humaneye, by moving, for example, the transparent spectral range of themirror glass along the wavelength axis such that the transmissionreaches a maximum value and covers at the same time the sensitivitymaximum of the CCD or CMOS camera. The auxiliary lighting unit isadvantageously realized by infrared LEDs which emit a light in thewavelength range which is within the transmission range of thereflective layer and for which the camera has the required sensitivity.

[0008] The camera is advantageously connected to the electric powersupply of the motor vehicle. The video images taken by it can be shownon a monitor. However, it is also possible to store the video images ona storage medium, for example, a video tape, a hard disk etc. It is alsopossible to store the image and simultaneously show it on a monitor.

BRIEF DESCRIPTION OF THE DRAWING

[0009] In the drawing:

[0010]FIG. 1 is a side view illustrating schematically a deviceaccording to the invention;

[0011]FIG. 2 shows in an illustration corresponding to that of FIG. 1 asecond embodiment of a device according to the invention;

[0012]FIG. 3 is an illustration corresponding to FIG. 1 of a thirdembodiment of the device according to the invention;

[0013]FIG. 4 is a view of an interior rearview mirror for a motorvehicle with the device according to the invention being arranged in theinterior rearview mirror;

[0014]FIG. 5 is a schematic sectional illustration of the interiorrearview mirror according to FIG. 4;

[0015]FIG. 6 shows a different embodiment of an interior rearview mirrorfor a motor vehicle in a representation similar to that of FIG. 4;

[0016]FIG. 7 is a schematic sectional illustration of the interiorrearview mirror according to FIG. 6;

[0017]FIG. 8 shows another embodiment of an interior rearview mirror fora motor vehicle in a representation similar to that of FIG. 4;

[0018]FIG. 9 is a schematic sectional illustration of the interiorrearview mirror according to FIG. 8;

[0019]FIG. 10 shows a further embodiment of an interior rearview mirrorfor a motor vehicle in a representation similar to that of FIG. 4;

[0020]FIG. 11 is a schematic sectional illustration of the interiorrearview mirror according to FIG. 10;

[0021]FIG. 12 shows another embodiment of an interior rearview mirrorfor a motor vehicle in a representation similar to that of FIG. 4;

[0022]FIG. 13 is a schematic sectional illustration of the interiorrearview mirror according to FIG. 12;

[0023]FIG. 14 shows another embodiment of an interior rearview mirrorfor a motor vehicle in a representation similar to that of FIG. 4;

[0024]FIG. 15 is a schematic sectional illustration of the interiorrearview mirror according to FIG. 14.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025]FIG. 1 shows an electrochromic mirror glass 1 for interiorrearview mirrors of motor vehicles. The electrochromic mirror glass 1has at approximately half its thickness a receptacle 2 for anelectrochromic liquid 3. The driver of the motor vehicle looks onto themirror glass 1 in the viewing direction illustrated by arrow 4. At thebackside of the electrochromic mirror glass 1, facing away from thedriver, a backside interference reflective layer 5 is provided. Theinterference reflective layer 5 extends advantageously across the entirebackside of the electrochromic mirror glass 1. As a result of thedescribed configuration, the electrochromic mirror glass has four sides6 to 9. The interference reflective layer 5 is provided on the side 9 ofthe electrochromic mirror glass 1 facing away from the driver.

[0026] A camera 10 is positioned behind the electrochromic mirror glass.The camera 10 is advantageously a CCD or CMOS camera. This camera 10 isdesigned to take video images. In the case that the illumination for thecamera 10 is not sufficient, light sources 11 are provided which areadvantageously in the form of LEDs. The light sources 11 are provided ina number which provide sufficient illumination and emit a wavelength forwhich the electrochromic mirror glass 1 is sufficiently transparent andfor which the employed camera 10 has a sufficient sensitivity. Dependingon the light conditions, the light sources 11 can be switched on inorder to obtained optimally lighted video images.

[0027]FIG. 2 shows the possibility of providing the interferencereflective layer 5 on the third side 8 in direct contact with theelectrochromic liquid 3. Since the interference reflective layer 5 isnot provided at the backside of the electrochromic mirror glass 1, itnow provides a front side interference reflective layer. In otherrespects, the electrochromic mirror glass 1 as well as the camera 10 andthe light sources 11 are of the same configuration as in the previouslydescribed embodiment.

[0028]FIG. 3 shows the possibility of using the camera 10 when noelectrochromic mirror glass is present: the conventional mirror glass 12according to FIG. 3 has only two sides, i.e., the front side 13 facingthe driver and the backside 14. The interference reflective layer 5 canbe provided, as desired, on the front side 13 or the backside 14. Thedriver looks again in the viewing direction of arrow 4 onto the mirrorglass 12. The camera 10 behind the mirror glass 12 is oriented in thedirection of arrow 15. It can be embodied according to the previousembodiments as a CCD or CMOS camera. In addition, light sources 11 canbe provided which, in accordance with the preceding embodiments, arealso located on the side of the mirror glass 12 facing away from thedriver in the viewing direction 4 of the driver.

[0029]FIGS. 4 and 5 show an interior rearview mirror 16 with a mirrorhousing 17 having the mirror glass 1 or 12 inserted therein at its openfront side. The camera 10 is positioned behind the mirror glass 1, 12 inthe lower left corner of the interior rearview mirror 16 which isrectangular in a plan view. The camera 10, as illustrated in FIG. 5, isarranged to be slightly slanted to the rear. The light sources 11 arearranged behind the mirror glass 1, 12 in the form of a matrix, i.e.,arranged in rows adjacent and underneath one another (rows and columns;see FIG. 4 ). They are advantageously provided over the entire backsideof the mirror glass 1, 12 with the exception of the area of the camera10. The arrangement according to FIGS. 4 and 5 is advantageous, inparticular, when a conventional (non-electrochromic) mirror glass 12 isused for the interior rearview mirror 16.

[0030] When the interior review mirror 16 is provided with anelectrochromic mirror glass 1 (FIGS. 6 and 7), the light sources 11,which, in accordance with the preceding embodiments, are infraredsending LEDs, are advantageously positioned on the rim 18 of the mirrorhousing 17. When a conventional titanium or chromium ortitanium-chromium layer is used as the reflective layer, thetransmission in conjunction with the darkened electrochromic layer canalready be so minimal that additional illumination may be required.Advantageously, an infrared illumination is selected that is within aspectral range of the camera sensitivity. Since the losses become toolarge as a result of double penetration of the reflective layer and theelectrochromic layer 3 (FIG. 1), the infrared sending LEDs areadvantageously arranged on the rim 18 of the mirror housing 17. The rim18 is comprised of plastic material which is transparent for theinfrared radiation of the light sources 11 but is opaque with regard tothe portion of the electromagnetic spectrum visible to the human eye.This ensures that the driver or the passengers do not see the lightsources 11. In other respects, the interior rearview mirror 16 isidentical to the embodiment according to FIGS. 4 and 5.

[0031] The camera 10 can be arranged at any suitable location behind themirror glass 1, 12. It is of such a configuration that it covers therequired viewing area for the respective application. Since additionaldevices, such as garage door openers, electrochromic electronic devices,memory drive and others, are often arranged in the interior rearviewmirror, the camera 10 is arranged such that the function of thesedevices is not impaired.

[0032] In the described embodiments and the still to be explainedembodiments an auxiliary lighting unit for additional illumination canbe provided external to the interior rearview mirror 16, depending onthe spatial conditions inside the motor vehicle. For example, such anauxiliary lighting unit can be integrated into the interior rear lightand/or dome light and/or reading light for the passengers seated in therear of the automobiles and/or busses. It is also possible to providethe auxiliary lighting unit in the A, B, C, or D columns or any othercolumn within the motor vehicle.

[0033] In special individual situations an image-transmitting fiberbundle 19 (FIGS. 8 and 9) can be connected to the camera 10. The opticsof these fiber bundles 19 have a diameter down to a magnitude as smallas 1 mm. The camera 10, in contrast to the previous embodiments, can bearranged in the mirror housing 17 without having a direct view of theinterior of the vehicle.

[0034] The image is taken by means of the optics 20 on the head of thefiber bundle 19 and guided to the light-sensitive areas of the camera10. The optical head 20 is preferably mounted in an opening 21 on themirror frame or rim 18. The light sources 11 are provided, as in theembodiment according to FIGS. 6 and 7, on the rim 18 of the mirrorhousing 17. The infrared sending LEDs 11, in accordance with theprevious embodiments, are distributed uniformly over the entirecircumference of the rim 18 of the mirror housing 17.

[0035]FIGS. 10 and 11 show an embodiment in which the optical head 20 ofthe fiber bundle 19 is arranged behind the infrared-transparent mirrorglass 1, 12. Since the mirror glass 1, 12 is opaque to the human eye,the camera 10 and the fiber bundle 19 cannot be seen by the passengers.In other respects, the interior rearview mirror 16 is of identicaldesign as the embodiment according to FIGS. 8 and 9.

[0036]FIGS. 12 and 13 show an interior rearview mirror 16 in which theoptical head 20 of the fiber bundle 19 is arranged according to theprevious embodiment behind the mirror glass 1, 12. The infrared-sendingLEDs 11 are arranged behind the mirror glass 1, 12 in rows and columns,forming a matrix. Advantageously, the light sources 11 are uniformlyarranged across the entire backside of the mirror glass 1, 12.

[0037] As an alternative to the active illumination by means of theinfrared sending LEDs 11, a lower light level intensifier tube 22 (FIGS.14 and 15) can be integrated in front of the camera optics. The lowerlight level intensifier tube 22 forms an image intensifier tube or imageconverter tube which, even under extremely bad lighting conditions,allows for a reliable monitoring of the interior of the vehicle in thevisible and in the near infrared wavelength ranges. The camera 10 isarranged behind the mirror glass 1, 12 in the mirror housing 17.Depending on the application, the camera is arranged in the mirrorhousing 17 such that it covers the required viewing area for theparticular application.

[0038] In order for the camera 10 to be invisible from the interior ofthe vehicle, the backside of the mirror glass 1, 12, with the exceptionof the opening 21 for the optical head 20 of the fiber bundle 19 (FIGS.8 and 9), is covered with a black lacquer in the described embodiments.In the case that the infrared auxiliary lighting unit 11 is to be usedbehind the mirror glass 1, 12, the lacquer is transparent for infraredlight of the respective wavelength, but is opaque in the visiblewavelength range. The optics are dereflected and mounted from behind aswell as from the side in a light-sealing way on the backside of themirror glass 1, 12 such that lateral scattered light cannot penetratethrough the reflective layer and cannot be seen by the end user, forexample, the driver.

[0039] The camera 10 can be used for a broad range of applications. Forexample, it can be used for driver identification, for monitoring thedriver's condition, for identifying passengers and passenger positions,for airbag control, for theft surveillance, and similar purposes. Forexample, it is possible to connect the camera 10 with the electricalsystem of the vehicle so that the vehicle can be started only when theauthorized driver is seated behind the steering wheel of the motorvehicle. Moreover, it is possible to trigger a warning signal should thedriver fall asleep behind the steering wheel.

[0040] While specific embodiments of the invention have been shown anddescribed in detail to illustrate the inventive principles, it will beunderstood that the invention may be embodied otherwise withoutdeparting from such principles.

What is claimed is:
 1. A monitoring device for vehicles, said monitoringdevice comprising: a housing (17); at least one mirror glass (1, 12)arranged in said housing (17) so as to have a front side facing anobserver; said at least one mirror glass (1, 12) comprising a reflectivelayer (5) being reflective in the visible spectral range of light; atleast one camera (10) arranged behind said reflective layer (5) in aviewing direction viewed from said front side.
 2. The monitoring deviceaccording to claim 1 , wherein said reflective layer (5) is selectedfrom the group consisting of an interference reflective layer, achromium reflective layer, a titanium reflective layer, and atitanium-chromium reflective layer.
 3. The monitoring device accordingto claim 1 , wherein said mirror glass (1) is an electrochromic mirrorglass or a conventional mirror glass.
 4. The monitoring device accordingto claim 3 , wherein said electrochromic mirror glass has anelectrochromic layer and wherein said reflective layer is arrangedbehind said electrochromic layer in said viewing direction.
 5. Themonitoring device according to claim 1 , comprising an auxiliarylighting unit (11) configured to provide additional light for said atleast one camera (10).
 6. The monitoring device according to claim 5 ,wherein said auxiliary lighting unit (11) emits light of a wavelengthable to pass through said reflective layer (5).
 7. The monitoring deviceaccording to claim 5 , wherein said auxiliary lighting unit (11) emitslight having a wavelength outside of the visible spectral range oflight.
 8. The monitoring device according to claim 5 , wherein saidauxiliary lighting unit (11) comprises light-emitting diodes.
 9. Themonitoring device according to claim 8 , wherein said light emittingdiodes emit light in the infrared range.
 10. The monitoring deviceaccording to claim 5 , wherein said auxiliary lighting unit (11) isarranged behind said reflective layer (5) in said viewing direction. 11.The monitoring device according to claim 5 , wherein said auxiliarylighting unit (11) comprises light-emitting diodes arranged in a matrixof rows and columns.
 12. The monitoring device according to claim 5 ,wherein said housing (17) and said mirror glass (1, 12) form an interiorrearview mirror (16), wherein said housing (17) has a rim (18), andwherein said auxiliary lighting unit (11) comprises light-emittingdiodes (11) arranged on said rim (18) of said housing (17).
 13. Themonitoring device according to claim 12 , wherein said rim (18) iscomprised of a material that is opaque to the human eye.
 14. Themonitoring device according to claim 1 , comprising animage-transmitting fiber bundle (19) connected to said at least onecamera (10).
 15. The monitoring device according to claim 14 , whereinsaid fiber bundle (19) has an optical head (20) resting against abackside of said mirror glass (1, 12).
 16. The monitoring deviceaccording to claim 14 , wherein said fiber bundle (19) has an opticalhead (20) and is arranged together with said optical head (20) on saidrim (18).
 17. The monitoring device according to claim 1 , wherein saidat least one camera (10) comprises a low light level intensifier (22).18. The monitoring device according to claim 17 , wherein said low lightlevel intensifier (22) is arranged behind said mirror glass (1, 12) insaid viewing direction.